Hello to all users! Sorry if not in the subject) 
I have developed a small website designed for all students, schoolchildren and technical specialists who work with the construction of graphs of functions and mathematics! 
My platform will help you create charts absolutely for free. This is a great solution for those who want to visualize functions and find useful examples of already constructed graphs. 
On the website https://mat4ast.info/example-graphs/trigonometric-graphs/cosine/
  you can simultaneously plot multiple graphs on a single image and instantly save screenshots on your computer or mobile device: 
My online platform provides a convenient graphical constructor that is suitable for constructing a variety of functions: linear, trigonometric, logarithmic, square, cubic, power, root functions, fractional and many others. 
Eg: 
[url=https://mat4ast.info/example-graphs/trigonometric-graphs/cosine/]graphs of the cos function [/url]
[url=https://mat4ast.info/example-graphs/quadratic/ ]construct graphs of quadratic functions [/url]
[url=https://mat4ast.info/example-graphs/line-function-ex/ ]Graph of Linear Function Online [/url]
[url=https://mat4ast.info/example-graphs/root/ ]Graphs of the square root function [/url]
[url=https://mat4ast.info/example-graphs/trigonometric-graphs/cotangent/ ]Graphs of the ctg cotangent function [/url]
 
I would really like to hear your opinion about the usefulness and convenience of my charting service. If you are satisfied with the result, I would appreciate it if you share a link to my platform on social networks. 
Also, if you have any comments or suggestions, feel free to contact me personally via private messages or the contact form on the website. I will definitely take into account your feedback and implement useful tips in practice. 
I wish you all good luck in your exams and in your scientific research!